There are many situations where it is desirable to provide an object with a high degree of visibility. For example, pedestrians, cyclists and children are particularly vulnerable to vehicle accidents at night, especially on roads with no sidewalk. It is common practice for such persons to wear reflective clothing or arm bands, but these can only be seen when the person is sufficiently close to the oncoming vehicle for enough light to be reflected.
Sometimes people will carry a conventional flashlight, but this can often only be seen in one direction and generally portable flashlights have a short lifetime, which means that they soon start to fade and become less visible.
Problems also arise in industrial environments where visibility is obscured due to dust or darkness, such as in underground mines, open pit mines, construction sites and the like. In such environments, there is often a danger of personnel being run over or caught by moving machinery, and it is vitally important to make the machinery as visible as possible so as to give the personnel sufficient time to move out of its way.
In all these situations, the warning time for the person in danger or operator of the vehicle is of the essence. For example, in the case of a fast-moving vehicle, a fraction of a second can make the difference between life and death. A vehicle moving at 60 miles an hour covers about 30 meters in one second.
Strobe lights, such as are found near road works, are known. These generally require substantial amounts of power and are therefore not conveniently portable and cannot be left unattended for prolonged periods. They are also not suitable for attachment to personnel, largely as a result of their bulk and weight.
Devices with flashing lights are known. For example, one such device is described in U.S. Pat. Nos. 3,944,803 and 3,134,548. These devices are unsatisfactory because the incandescent bulbs they employ consume a large amount of power and they therefore have a short lifetime. When incandescent bulbs are periodically switched on and off their lifetime is considerably shortened.
A problem with all such devices is how to find a safe, longlasting, high energy power pack. Lithium batteries provide a convenient source of high energy power, but can be extremely dangerous if allowed to discharge too rapidly. Their high energy density can cause them to explode if shorted either directly or as a result of the ingress of moisture.
An object of the present invention is to alleviate the aforementioned problems and provide a portable safety device with high visibility and longevity.